In recent years, the introduction of a train control system that uses radio communication called “communication based train control” (CBTC) has been ongoing. Although the wireless communication scheme is not prescribed for CBTC, systems using 2.4-GHz band radio communication are mainstream. The 2.4-GHz band radio communication is exemplified in IEEE 802.11b/g. The 2.4-GHz band is also referred to as an “ISM (Industry Science Medical) band”, and it has been used for short range wireless communication systems that have been rapidly coming into widespread use in recent years and has also been used in many devices, such as a microwave ovens. Examples of short range wireless communication systems include wireless communication systems using IEEE 802.11b,g, Bluetooth (registered trademark), and Zigbee (registered trademark).
In the ISM band, the areas where devices are used is not restricted; therefore, there is a problem in that the radio waves from a plurality of apparatuses interfere with each other and thus the communication quality of a wireless communication system deteriorates. Accordingly, in order to realize wireless communication with high quality in a train wireless system that uses an ISM band, a technology is indispensable that suppresses deterioration in communication quality caused by interfering radio waves from other devices. For example, a train wireless communication system disclosed in Patent Literature 1 is configured such that, on the basis of a channel search result, the terminal mounted on the fore side car of a train and the terminal mounted on the rear side car of the train select, from among the frequency channels having a reception intensity equal to or higher than a threshold, frequency channels different from each other. This configuration enables wireless communication to continue even if one of the channels is subjected to interference.